Abstract This paper addresses the automatic generation control of deregulated multi area power system including one of the most important renewable energy resource viz. wind power plant. The interconnected two area power system is thermal-hydro system with two GENCOs in thermal area and one GENCO in hydro area. Generation rate constraint (GRC) is considered in all the GENCOs separately. Integral square error technique is used to optimize the gains of various integral controllers. It is seen that system response becomes poorer in terms of peak overshoots and settling time by considering GRC. DISCO participation matrix is chosen on the basis of open market strategy which is continuously changing. So, effect of changing DPM on dynamic responses is studied, following a step load perturbation. It is revealed that there is no effect of changing DPM on system’s dynamic responses. Keywords – Automatic generation control (AGC), deregulated power system, DISCO participation matrix (DPM), wind turbines, generation rate constraint (GRC).